PI Signal Strength vs. Cable length

[Christian]

Hello,

I understand that the signal strength on a PI metal detector (just as on any other device) will weaken the longer the cable length gets.

I wondered if anybody knew which technical means can be taken against the signal loss?

Any advice is most welcome.

Thank yoU!

[Max]

Hello,

I understand that the signal strength on a PI metal detector (just as on any other device) will weaken the longer the cable length gets.

I wondered if anybody knew which technical means can be taken against the signal loss?

Any advice is most welcome.

Thank yoU!

Hi,
one simple way will be putting a preamplifier board with IC and all passive components at few distance from search coil... then you'll get amplified signal and can then use a longer cable (if needed) to connect to a far away control box.

This will act as a repeater/amplifier for the signal.

The signal loss is not the only problem: when cable is long there are also capacitive effects to consider... any e.g. coaxial cable has a specified capacitance/meter then you must consider that doubling the lenght will about double capacitance... since this will made impossible sampling at very low first delay the best, also for this reason, will be using a near preamp and then a longer cable to control box.

In some existent designs (e.g. minelab) there is sometimes a small PCB inside coil housing ... in other there is an external preamp at less than 1m from coil... much depends on kind of system... you know... an airport/security walkthrough detector have a different need of long cabling (often 5-6meters) than a beach detector (1m range)... a "food" detector could have even 10meters far control box... a gold mine detector could have coil near rocks transport system and control box even 100meters or more away to keep electronics far from dust , noise , vibrations etc.

Best regards,
Max